U.S. patent application number 17/307930 was filed with the patent office on 2021-11-11 for system and method for coating thin elongate parts.
The applicant listed for this patent is SST Systems, Inc.. Invention is credited to Bradley M. Andreae, Anthony C. Scoville, Joseph Wildenberg.
Application Number | 20210348295 17/307930 |
Document ID | / |
Family ID | 1000005612874 |
Filed Date | 2021-11-11 |
United States Patent
Application |
20210348295 |
Kind Code |
A1 |
Andreae; Bradley M. ; et
al. |
November 11, 2021 |
SYSTEM AND METHOD FOR COATING THIN ELONGATE PARTS
Abstract
In one aspect, the invention provides a coating process system
including a continuous conveyor, a first end defining a loading
station for loading work pieces to the conveyor, and a second end
defining an unloading station for unloading work pieces from the
conveyor. A series of workstations is configured to render coated
work pieces and arranged at a first level to extend between the
first and second ends. A cure oven is arranged at a second level
above the first level, the conveyor making a plurality of runs
between the first and second ends at different sub-levels within
the second level. A first post-oven run of the conveyor extends
from an outlet of the cure oven to the unloading station. A second
post-oven run of the conveyor extends from the unloading station to
the loading station.
Inventors: |
Andreae; Bradley M.;
(Sturgeon Bay, WI) ; Wildenberg; Joseph;
(Brussels, WI) ; Scoville; Anthony C.; (Sturgeon
Bay, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SST Systems, Inc. |
Sturgeon Bay |
WI |
US |
|
|
Family ID: |
1000005612874 |
Appl. No.: |
17/307930 |
Filed: |
May 4, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63156234 |
Mar 3, 2021 |
|
|
|
63020783 |
May 6, 2020 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 5/50 20130101; C25D
17/06 20130101 |
International
Class: |
C25D 17/06 20060101
C25D017/06; C25D 5/50 20060101 C25D005/50 |
Claims
1. A coating process system comprising: a continuous conveyor; a
first end defining a loading station for loading work pieces to the
conveyor; a second end defining an unloading station for unloading
work pieces from the conveyor; a series of workstations configured
to render coated work pieces and arranged at a first level to
extend between the first and second ends; and a cure oven arranged
at a second level above the first level, the conveyor making a
plurality of runs between the first and second ends at different
sub-levels within the second level, wherein a first post-oven run
of the conveyor extends from an outlet of the cure oven to the
unloading station, and wherein a second post-oven run of the
conveyor extends from the unloading station to the loading
station.
2. The coating process system of claim 1, wherein the series of
workstations form an electrocoating process line, the coating
station including a liquid bath containing suspended,
electrically-charged paint particles.
3. The coating process system of claim 1, further comprising a
plurality of carriers coupled to the conveyor for supporting
respective work pieces, wherein the plurality of carriers are
configured to maintain continuous possession of the respective work
pieces from the loading station to the unloading station.
4. The coating process system of claim 1, wherein both the first
and second post-oven runs of the conveyor extend above the cure
oven, the first post-oven run extending through a third level above
the second level, and the second post-oven run extending through a
fourth level above the third level.
5. The coating process system of claim 1, further comprising one or
more cleaning workstations located along the second post-oven run
of the conveyor and configured to clean empty work piece carriers
as they are conveyed from the unloading station to the loading
station.
6. The coating process system of claim 1, wherein the series of
workstations at the first level extend along a linear path between
the first and second ends.
7. The coating process system of claim 1, further comprising a
plurality of carriers, each of the plurality of carriers adapted to
carry a plurality of work pieces across a direction transverse to a
direction of travel of the conveyor.
8. The coating process system of claim 7, wherein each of the
plurality of carriers spans between a first pair of separate,
laterally-spaced conveyor chains of the conveyor to act as a
lateral load bar for the plurality of work pieces.
9. The coating process system of claim 8, further comprising an
additional plurality of carriers, each adapted to carry a plurality
of work pieces across the transverse direction, each of the
additional plurality of carriers spanning between a second pair of
separate, laterally-spaced conveyor chains of the conveyor.
10. A coating process system comprising: a series of workstations
configured to prepare and coat a work piece suspended from a
continuous conveyor extending along the series of workstations; a
loading station at which the work piece is coupled to the conveyor
at an upstream end of the series of workstations; a cure oven
having an inlet located adjacent a downstream end of the series of
workstations along the conveyor, the cure oven extending above the
series of workstations, the conveyor making a plurality of
sequential, back-and-forth runs where each run extends across the
cure oven at a different height; an unloading station at which the
work piece is removed from the conveyor; and a post-oven run of the
conveyor extending from the unloading station to the loading
station.
11. The coating process system of claim 10, wherein the post-oven
run of the conveyor extends over top of the cure oven.
12. The coating process system of claim 10, wherein a length of the
cure oven is no more than 1.1 times a length of the series of
workstations between the upstream and downstream ends.
13. The coating process system of claim 10, wherein the plurality
of sequential, back-and-forth runs of the conveyor across the cure
oven includes at least three runs.
14. The coating process system of claim 10, wherein the series of
workstations form an electrocoating process line including a
coating station in which a liquid bath contains suspended,
electrically-charged paint particles.
15. The coating process system of claim 10, further comprising a
carrier coupled to the conveyor for supporting the work piece, the
carrier configured to maintain continuous possession of the work
piece from the loading station to the unloading station.
16. The coating process system of claim 15, wherein the carrier
spans between a pair of separate, laterally-spaced conveyor chains
of the conveyor to act as a lateral load bar for a plurality of
work pieces including the work piece.
17. The coating process system of claim 10, wherein an outlet of
the cure oven is located at a common end of the coating process
system as the loading station, the coating process system further
comprising an additional post-oven conveyor run extending over top
of the cure oven from the cure oven outlet to the unloading
station.
18. The coating process system of claim 10, further comprising one
or more cleaning workstations located along the post-oven run of
the conveyor and configured to clean empty work piece carriers as
they are conveyed from the unloading station to the loading
station.
19. The coating process system of claim 10, wherein the series of
workstations extend along a linear path between the upstream and
downstream ends.
20. A coating process system comprising: a continuous conveyor; a
series of workstations arranged along a path of the conveyor and
configured to prepare and coat a work piece carried by the
conveyor, the series of workstations defining a length measured
between respective upstream and downstream ends thereof; and a cure
oven having an inlet located adjacent the downstream end of the
series of workstations along the conveyor, the cure oven extending
over top of the series of workstations, wherein, measured parallel
to the length of the series of workstations, the cure oven defines
a length no more than 1.1 times the length of the series of
workstations, and wherein the conveyor makes at least three
lengthwise runs through the cure oven at different heights such
that, for any given conveyor speed, a residence time of the work
piece in the cure oven is more than double a total residence time
within the series of workstations.
21. The coating process system of claim 20, wherein a post-oven run
of the conveyor extends over top of the cure oven to deliver the
work piece to an unloading station and/or deliver an empty work
piece carrier from the unloading station to a loading station
adjacent the upstream end of the series of workstations.
22. The coating process system of claim 20, further comprising one
or more cleaning workstations located along the post-oven run of
the conveyor and configured to clean empty work piece carriers as
they are conveyed from the unloading station to the loading
station.
23. The coating process system of claim 20, further comprising a
carrier coupled to the conveyor for supporting the work piece, the
carrier configured to maintain continuous possession of the work
piece throughout a full cycle of the coating process system.
24. The coating process system of claim 23, wherein the carrier
spans between a pair of separate, laterally-spaced conveyor chains
of the conveyor to act as a lateral load bar for a plurality of
work pieces including the work piece.
25. The coating process system of claim 20, wherein the series of
workstations form an electrocoating process line including a
coating station in which a liquid bath contains suspended,
electrically-charged paint particles.
26. The coating process system of claim 20, wherein the series of
workstations extend along a linear path between the upstream and
downstream ends.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 63/020,783 filed on May 6, 2020, and to U.S.
Provisional Patent Application No. 63/156,234 filed on Mar. 3,
2021, the entire contents of both of which are incorporated by
reference herein.
BACKGROUND
[0002] The present invention relates to finishing systems and
processes for manufactured parts, and more particularly to carriers
for transporting manufactured parts through a finishing process and
methods relating to the same.
SUMMARY
[0003] In one aspect, the invention provides a coating process
system including a continuous conveyor, a first end defining a
loading station for loading work pieces to the conveyor, and a
second end defining an unloading station for unloading work pieces
from the conveyor. A series of workstations is configured to render
coated work pieces and arranged at a first level to extend between
the first and second ends. A cure oven is arranged at a second
level above the first level, the conveyor making a plurality of
runs between the first and second ends at different sub-levels
within the second level. A first post-oven run of the conveyor
extends from an outlet of the cure oven to the unloading station. A
second post-oven run of the conveyor extends from the unloading
station to the loading station.
[0004] In another aspect, the invention provides a coating process
system including a series of workstations configured to prepare and
coat a work piece suspended from a continuous conveyor extending
along the series of workstations. A loading station is provided at
which the work piece is coupled to the conveyor at an upstream end
of the series of workstations. A cure oven has an inlet located
adjacent a downstream end of the series of workstations along the
conveyor, the cure oven extending above the series of workstations.
The conveyor makes a plurality of sequential, back-and-forth runs
where each run extends across the cure oven at a different height.
An unloading station is provided at which the work piece is removed
from the conveyor. A post-oven run of the conveyor extends from the
unloading station to the loading station.
[0005] In yet another aspect, the invention provides a coating
process system including a continuous conveyor and a series of
workstations arranged along a path of the conveyor and configured
to prepare and coat a work piece carried by the conveyor. The
series of workstations defines a length measured between respective
upstream and downstream ends thereof. A cure oven has an inlet
located adjacent the downstream end of the series of workstations
along the conveyor, the cure oven extending over top of the series
of workstations. Measured parallel to the length of the series of
workstations, the cure oven defines a length no more than 1.1 times
the length of the series of workstations. The conveyor makes at
least three lengthwise runs through the cure oven at different
heights such that, for any given conveyor speed, a residence time
of the work piece in the cure oven is more than double a total
residence time within the series of workstations.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a plan view cross-section of a magnetic work piece
carrier according to a first embodiment of the present
disclosure.
[0007] FIG. 2 is a front view cross-section of the magnetic work
piece carrier of FIG. 1.
[0008] FIG. 3 is a side view cross-section of the magnetic work
piece carrier of FIGS. 1 and 2.
[0009] FIG. 4 is a front view of an exemplary work piece.
[0010] FIG. 5 is a first perspective view of a magnetic work piece
carrier according to a second embodiment of the present
disclosure.
[0011] FIG. 6 is a second perspective view of the magnetic work
piece carrier of FIG. 5.
[0012] FIG. 7 is a front view of the magnetic work piece carrier of
FIG. 5.
[0013] FIG. 8 is a side elevation view of the magnetic work piece
carrier of FIG. 5.
[0014] FIG. 9 is a plan view of a coating system according to a
third embodiment of the present disclosure.
[0015] FIG. 10 is a side elevation view of the coating system of
FIG. 9.
[0016] FIG. 10A is a detail view of a portion of the coating system
identified in FIG. 10.
[0017] FIG. 10B is a detail view of another portion of the coating
system identified in FIG. 10.
[0018] FIG. 11 is a cross-section view of the coating system of
FIGS. 9 and 10.
[0019] FIG. 12 is a side elevation view of several work piece
carriers holding work pieces along a conveyor chain.
DETAILED DESCRIPTION
[0020] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways.
[0021] A work piece carrier 20 or "holder" is illustrated in FIGS.
1-3. The carrier 20 can be a single piece or an assembly of
multiple pieces adapted to hold one or a plurality of work pieces
24, and further adapted to be conveyed through multiple
workstations 28 of an industrial process such as a coating process.
Although not shown, the carrier 20 can include one or more load
bars configured to be engaged by a conveyor as part of a conveyor
system, e.g., an overhead conveyor and more particularly an
indexing conveyor, as the coating or other process can be a
conveyorized process. As illustrated, the conveyor can include one
or more rails 32 that extend along a primary direction of travel A.
In some constructions, the conveyor can be a SlideRail Square
Transfer system such as that provided by SST Systems, Inc. of
Sturgeon Bay, Wis. and according to aspects of the disclosure of
U.S. Pat. No. 5,012,918 and/or U.S. Pat. No. 4,942,956, the entire
contents of which are incorporated by reference herein. The carrier
20 includes one or more conveyor interfaces 36 so that the conveyor
can engage and transport the carrier 20. As illustrated, these
conveyor interfaces 36 are provided as horizontal flanges. One or
more of the workstations 28 can include liquid baths into which the
work pieces 24 and at least a portion of the carrier 20 are
immersed during the process of applying a finish coating (e.g.,
paint) to the work pieces 24. The process can be an electrocoat or
"e-coat" process by which electric charge attraction is used to
apply suspended paint particles (resin and pigment) from the liquid
bath onto the exposed (and electrically-conductive) surface of the
work pieces 24. In other constructions, the carrier 20 or a
modified form thereof may be used in other surface finish or
coating processes, such as without limitation, liquid spray paint,
powder coating, or electroplating.
[0022] Each work piece 24 is supported by the carrier 20 in fixed
relationship therewith, without any means of clamping, gripping, or
grasping. The work pieces 24 can be supported "on-edge" along a
support surface 40 of the carrier 20. The support surface 40
extends horizontally and forms a bottom surface of the carrier 20
as illustrated, with the work piece 24 suspended from the support
surface 40. However, the work pieces 24 can be coupled to any one
of a top, bottom, or side of the carrier 20 (e.g., horizontal,
vertical, or angled). The support surface 40 of the carrier 20 can
include one or more predetermined receptacles or locators 42 in the
form of pockets, notches, or slots for receiving a portion, in
particular an edge (and more particularly a thinnest edge), of each
work piece 24. In the illustrated construction, the work pieces 24
are coupled to the carrier 20 exclusively by magnetic attraction.
The carrier 20 has an interior compartment 46 in which one or more
magnets 48 are provided. The magnets 48 can be permanent magnets
(e.g., Neodymium, such as AH series high temperature Neodymium
available from Magma Magnetic Technologies Ltd.). However, it may
be possible in some constructions to provide electromagnet(s) that
can be powered on and off to selectively generate a magnetic field.
High temperature magnets 48 may facilitate further conveyance of
the work pieces 24 with the carrier 20 through a heated workstation
(e.g., an industrial oven or conveyor oven) for drying/curing the
applied coating as part of the coating process. Oven temperatures
may be in excess of 300 degrees Fahrenheit, and in some
constructions up to at least 400 degrees Fahrenheit. The magnets 48
can be cylindrical in cross-section. Each magnet 48 can be held in
a pocket or receptacle 50, or otherwise fixed in place (e.g., with
fasteners and/or adhesive) to define an attachment location for one
or more work pieces 24. As shown, the receptacles 50 are formed by
upstanding walls extending up from the bottom wall of the holder 20
that forms the support surface 40, although the receptacles can
alternately by formed by depressions or combinations thereof.
Although merely exemplary, the receptacles 50 are laid out in a
pattern of two parallel rows of three each along the conveyor
direction A. The central axis of each cylindrical magnet 48 can be
oriented parallel to the support surface 40 so that the cylinder is
lying down along the inside of the carrier wall forming the support
surface 40, rather than standing up from it. Thus, the magnetic
field is concentrated along a linear path directly below the magnet
48.
[0023] The work pieces 24, one of which is shown separate from the
carrier 20 in FIG. 4, are thin elongate parts having a length L, a
width W, and a height H. The width W and the height H make up the
cross-sectional shape or height-to-width ratio, taken in the plane
perpendicular to the length L. The cross-section can be uniform
along the length L as shown, or may vary through portions thereof.
The length L may be the longest dimension by a factor of at least 3
in some constructions. The work piece 24 has a thin cross section
in which the height H is substantially larger than the width W. For
example, the height-to-width ratio can be 6:1 or greater, such as
8:1 or greater, or 10:1 or greater. The height-to-width ratio may
be less than 25:1 in some constructions. Although the work piece
width W can be less than 12 mm, and less than 6 mm in some
constructions, the term "thin" is not used in reference to the
actual measure of size, but comparative dimensional size. Said
another way, the work pieces 24 are flat or sheet-form. Two
opposite flat sides of the sheet are formed by the length L and the
height H, and the work pieces 24 would normally only be stably
supported by lying on one of the flat sides as compared to being
stood up on-edge, which yields instability. As shown in the
drawings, the work pieces 24 engage with the carrier 20 along a
thin edge of the work piece 24 formed by the width W and the length
L, while the height H of the work piece 24 extends away from the
support surface 40 (e.g., perpendicular). Each work piece 24 can
have a length L that is the same as, smaller than, or larger than
the corresponding magnet length as shown in FIG. 2. As shown in
FIG. 3, the width W of the work piece 24 can be less than the
corresponding magnet width (e.g., diameter).
[0024] Returning to the locators 42 in the support surface 40 of
the carrier 20, these locators 42 can be formed with a length that
is at least as long as the work piece length L. The locators 42 can
accommodate a range of different lengths of work pieces up to the
length of the locators 42 themselves. Further, the width of the
locators 42 may taper along the depth direction, for example in a
"U" or "V" shape as viewed in the cross-section of FIG. 3. By
tapering down the width of the notches forming the locators 42,
work pieces of various widths W may be accommodated. The various
work pieces 24 will be received to a depth corresponding to their
width W, while making contact with both side walls in any case. It
is also further noted that the width W of some or all work pieces
24 may taper down toward the edge that is held in the locator 42.
Thus, the edge of the work piece 24 may be at least partially
complementary to the shape of the locator 42 in cross-section. In
some constructions, the work pieces 24 are cutting blades having
cutting edges (e.g., serrated) that are subject to wear during use
and need not be completely coated by the coating process, as the
coating would be worn off upon use. Thus, holding the cutting edge
against the support surface 40 is not necessarily a detriment to
the outcome of the coating process for the work piece 24.
Serrations or teeth of a cutting blade may be entirely received
into the locator 42 or only partially received therein. Although
the deepest portion of each locator 42 can be a straight line at
even depth as illustrated, it is also contemplated to have an
undulating or serrated shape within the locators 42. Restraining
each work piece 24 to the carrier 20 solely by magnetic attraction
along the thin edge allows the entire remaining surface of the work
piece 24 to be exposed to be coated completely and evenly without
any touch points. As shown in FIG. 3, a vast majority of the height
H of the work piece 24 is exposed and stands proud of the support
surface 40 (e.g., at least 80 percent, at least 90 percent).
[0025] The workstations 28 can include finishing stations,
including an electrocoating immersion tank for submerging the work
pieces 24 into an electrocoating liquid. However, the workstations
28 can also include other types of equipment, such as an oven, a
paint or powder coat spray station, and the like. An exemplary
electrocoating process line can include a pretreat workstation,
followed by an electrocoat workstation, followed by a post rinse
workstation, followed by a drying/curing workstation along the
conveyor. The work pieces 24 can remain connected to the carrier 20
throughout the entire process. The work pieces 24 remain untouched
from the beginning of the finishing process until after
drying/curing so there is no concern of contaminating or spoiling
the surface coating. During electrocoating, the work pieces 24 are
electrically grounded to receive the charged coating particles from
the liquid bath. In order to prevent the need for any separate
grounding connection placed on the surface of the work pieces 24,
the work pieces 24 are grounded through contact with the carrier
20. In particular, physical contact between the electrically
conductive work pieces 24 and the electrically conductive carrier
20 establishes ground connection. Both the carrier 20 and the work
piece 24 can be wholly or at least partially constructed of metal,
and the work piece 24 (or at least a portion thereof) is
ferromagnetic metal to exhibit attraction to the magnet 48. Contact
between the edge of the work piece 24 and the support surface 40 at
the locator 42, including nominal scraping during loading/unloading
(and potential micromovements during the process) prevents the
buildup of the coating material within the locator 42. Thus, the
carrier 20 may be used and re-used with little or no dedicating
cleaning or coating removal, allowing subsequent sets of work
pieces 24 to establish electrical grounding connection with the
carrier 20.
[0026] A process of conveying one or more work pieces 24 through a
finishing process can include the following steps. First, the work
piece 24 is/are secured to the carrier 20. This involves placement
of the work piece(s) 24 into the locators 42, either manually or
preferably through an automated handling process, e.g., by
registering the carrier 20 with a work piece holding cartridge or
tray and then performing a joining movement. The conveyor is
operated to transport the carrier 20 with the work pieces 24 to a
workstation 28. The conveyor may transport the work pieces 24
directly into the workstation 28 along the primary direction of
travel A, or may first transport the work pieces 24 to a position
above the workstation 28 (e.g., in the case of an immersion tank).
A vertical drive may lower the carrier 20 from the conveyor so that
the work pieces 24 are lowered into the workstation 28. The
vertical drive can include any suitable system for producing the
required vertical travel. Alternately, the conveyor may follow a
path that descends to allow the work pieces 24 to descend into the
workstation 28. The work pieces 24 can be lowered while traveling
along the conveyor or after stopping at a position along the
conveyor corresponding to the desired workstation 28. The carrier
20 is then transported via the conveyor to another workstation 28
or to an unloading station of the conveyor system. The work pieces
24 are only removed from the carrier 20 after drying/curing of the
applied coating.
[0027] FIGS. 5-8 illustrate another embodiment according to aspects
of the present disclosure. In this embodiment, a work piece carrier
120 or "holder" is alternately configured to that of FIGS. 1-3,
though also provided to magnetically hold one or more work pieces
24. The carrier 120 may be adapted to be conveyed through multiple
workstations 28 of an industrial process such as a coating process
as in the preceding description. Although not shown, the carrier
120 can include one or more load bars configured to be engaged by a
conveyor as part of a conveyor system, e.g., an overhead conveyor
and more particularly an indexing conveyor. Thus, the carrier 120
can include one or more conveyor interfaces so that the conveyor
can engage and transport the carrier 120. These conveyor interfaces
can be provided as horizontal flanges as disclosed above, or may
take other forms, e.g., chain interfaces for one or more conveyor
chains. For example, the work piece carrier 120 can take the form
of the carrier 20 as shown in FIGS. 1-2, with one or more of the
structures shown in FIGS. 5-8 replacing the portion between the
flanges 36. One or more of the workstations 28 can include liquid
baths into which the work pieces 24 and at least a portion of the
carrier 120 are immersed during the process of applying a finish
coating (e.g., paint) to the work pieces 24. The process can be an
electrocoat or "e-coat" process by which electric charge attraction
is used to apply suspended paint particles (resin and pigment) from
the liquid bath onto the exposed (and electrically conductive)
surface of the work pieces 24. In other constructions, the carrier
120 or a modified form thereof may be used in other surface finish
or coating processes, such as without limitation, liquid spray
paint, powder coating, or electroplating.
[0028] The work piece 24 is supported by the carrier 120 in fixed
relationship therewith, without any means of clamping, gripping, or
grasping. The work piece 24 can be supported "on-edge" along a
support surface 140 of the carrier 120. The support surface 140
extends horizontally and forms a bottom surface of the carrier 120
as illustrated, with the work piece 24 suspended from the support
surface 140. The support surface 140 of the carrier 120 can
cooperate to form one or more predetermined receptacles or locators
142 for receiving a portion of each work piece 24. As illustrated,
the locator 142 is formed as a notch, e.g., a 90-degree notch
forming an "L" shape (as viewed in the front elevation view of FIG.
7). Thus, the support surface 140 cooperates with an adjacent side
surface 140A extending vertically at a right angle with the
horizontal bottom support surface 140. In the illustrated
construction, the work pieces 24 are coupled to the carrier 120
exclusively by magnetic attraction to the support surface 140.
Although the carrier 120 does not clamp or grip the work piece 24
to physically restrain or retain it, the provision of the side
surface 140A inhibits or prevents certain movements of the work
piece 24 along the horizontal bottom surface 140, such as twisting
or swinging.
[0029] The carrier 120 has an end cap 146 providing the support
surface 140 and the side surface 140A, the end cap 146 separate
from one or more magnets 148 provided to magnetically attract and
retain the work piece 24. Thus, exposure to process chemical baths
and surface wear associated with interaction with the work piece 24
can be limited to the end cap 146 and kept from affecting the
magnet 148. The magnet 148 can be a permanent magnet (e.g.,
Samarium Cobalt Magnet (rated to 572 deg F.)). However, it may be
possible in some constructions to provide alternate magnets such
electromagnet(s) that can be powered on and off to selectively
generate a magnetic field. High temperature magnets 148 may
facilitate further conveyance of the work pieces 24 with the
carrier 120 through a heated workstation (e.g., an industrial oven
or conveyor oven) for drying/curing the applied coating as part of
the coating process. Oven temperatures may be in excess of 300
degrees Fahrenheit, and in some constructions up to at least 400
degrees Fahrenheit. The end cap 146 can be constructed partly or
entirely of 416 stainless steel or another martensitic stainless
steel, which allows transfer of the magnetic field with minimal
losses. The end cap 146 is one example of a contact element,
separate from the magnet(s) 148, that acts as a magnet-to-work
piece intermediary and takes on any surface wear on behalf of the
magnet(s) 148.
[0030] The magnets 148 can be cylindrical in cross-section. Each
magnet 148 can be held in an orientation that defines an attachment
location for one or more work pieces 24. The central axis of each
cylindrical magnet 148 can be oriented perpendicular to the support
surface 140. Thus, the magnetic field is concentrated along a
linear path directly below the magnet 148. The work pieces 24, only
a portion of which is shown in FIGS. 5-8, are thin elongate parts
having a length L, a width W, and a height H and may follow the
relationships set forth above. As such, the work pieces 24 are flat
or sheet-form. As shown in the drawings, the work piece 24 engages
with the surface 140 of the carrier 120 along a thin edge of the
work piece 24, while the length L of the work piece 24 extends away
from the support surface 140 (e.g., perpendicular). The surface
140A establishes supplementary contact with the surface 140A. The
direction of magnetic attraction on the work piece 24 may be
axially upward into the surface 140. The work piece 24 may have
relatively less magnetic attraction, or none, toward the surface
140A. The width W of the work piece 24 can be less than the
corresponding magnet width (e.g., diameter), or as shown, the work
piece 24 includes a reduced height tang portion 24A which is the
sole point of contact with the carrier 120. For example, the tang
portion 24A has a height H1 that is 50 percent or less of the
height H elsewhere on the work piece 24. Although the work piece 24
is not shown in full, a vast majority of the length L of the work
piece 24 is exposed and stands proud of the end cap 146 (e.g., at
least 80 percent, at least 90 percent, or at least 95 percent). An
entirety of the work piece length L extends below the support
surface 140 (i.e., the horizontal bottom-facing portion thereof).
Restraining the work piece 24 to the carrier 120 by magnetic
attraction as shown allows the entire remaining surface of the work
piece 24 to be exposed to be coated completely and evenly without
any touch points. Touch points may be limited to the tang portion
24A, or even a limited portion thereof. In other constructions, the
carrier 120 may be provided without the vertical surface 140A such
that the only contact point is the thin edge at one lengthwise end
of the work piece 24 (e.g., the rear edge of the tang portion 24A
having the height and width dimensions H1, W).
[0031] The carrier 120 can be used with workstations 28, for
example finishing stations including electrocoating immersion tank,
an oven, a paint or powder coat spray station, and the like, and
reference is hereby made to the preceding description and
drawings--although it is repeated that the work piece 24 can in
some constructions remain connected to the carrier 120 and
otherwise untouched throughout an entire multi-step process. In
order to prevent the need for any separate grounding connection
placed on the surface of the work pieces 24, the work pieces 24 are
grounded through contact with the carrier 120.
[0032] FIGS. 9-12 illustrate a work piece coating system 200
according to another aspect of the present disclosure. Although the
coating system 200 can take alternate forms and configurations in
other constructions, the coating system 200 is illustrated as an
electrocoating process that includes several immersion baths,
including one for immersing the work pieces 224 into a liquid bath
containing suspended, electrically-charged paint particles. As
shown in FIG. 12 and described in further detail below, the work
pieces 224 can be supported by carriers 220, which differ from
those described above. For example, the carriers 220 can be
hook-shaped or have hook portions and may support the work pieces
224 by the work pieces 224 resting on or hanging from the hooks
rather than by magnetic attraction. Each work piece carrier 220 is
coupled to move with movement of the conveyor system 207 at all
times. Further the work piece(s) 224 are engaged with their
respective carriers 220 for the duration of the process of the
system 200--in other words, the carrier 220 maintains possession of
the work piece 224 through the full process from a loading station
203 to an unloading station 205.
[0033] The work pieces 224 can be thin elongate parts as described
above, or differently shaped as in the illustrated construction
where the work pieces 224 are hole saws or other components that
may be described as round and/or hollow. Returning to FIGS. 9 and
10, the coating system 200 includes opposite first and second ends,
the first end having the work piece loading station 203 and the
second end having the work piece unloading station 205. As
appreciated more clearly from FIG. 10, the work pieces 224 travel a
circuitous or serpentine path between the two ends, rather than a
single pass from the first end to the second end. The path is
defined by a conveyor or conveyor system 207, which is continuous
and may be formed in various constructions, including as a chain
conveyor in the included drawings. The conveyor system 207 includes
one or more conveyor chains 209 and a number of sprockets that
direct the conveyor chains 209 around the path and/or power the
chain for movement about the path. As can be appreciated from FIG.
9, the conveyor system 207 may include multiple adjacent conveyor
tracks, which may be operated independently or synchronously (e.g.,
from a common drive). If operated with independence, the conveyor
system 207 may be said to have multiple conveyors, although the
multiple tracks of FIG. 9 are linked together to constitute a
single conveyor. As shown, a first conveyor track is defined by a
first pair of parallel, laterally spaced conveyor chains 209A, and
second conveyor track is defined by a second pair of parallel,
laterally spaced conveyor chains 209B. Work pieces 224 on a given
one of the conveyor tracks are positioned laterally between the
conveyor chains for that conveyor track, e.g., either between the
first conveyor chains 209A or between the second conveyor chains
209B. The same may be true for another construction in which there
is only a single conveyor track defined by a single pair of
conveyor chains 209.
[0034] From the loading station 203, the work pieces 224 are
conveyed through a series or workstations WS to carry out the
process (e.g., e-coat). A first group or series of workstations can
be arranged at a first level LV1 (FIG. 10) and may include a number
of immersion baths. The level refers to vertical height with
respect to a floor supporting the workstations, and the first level
LV1 may optionally start directly at a floor of an industrial
building. The workstations can include some or all of the following
in sequence: RO Rinse workstation (WS1), Cleaner workstation (WS2),
Counterflow Rinse 1 workstation (WS3), Counterflow Rinse 2
workstation (WS4), Counterflow Rinse 3 workstation (WS5), E-Coat
workstation (WS6), Permeate Rinse 1 workstation (WS7), and Permeate
Rinse 2 workstation (WS8). The workstation WS1 can be the first
workstation of the system 200 to perform any treatment on the work
pieces 224 once loaded to the conveyor 207. The workstations
WS1-WS8 render coated work pieces, the coating being uncured. FIGS.
10A and 10B show portions of the side elevation in greater detail.
From the final workstation WS8 of the first level workstations, the
work pieces 224 with uncured coatings applied are conveyed into a
cure oven 215 that is positioned at a second level LV2 above the
first level LV1. Within the cure oven 215, the conveyor 207 (e.g.,
each conveyor chain 209 thereof) makes multiple runs or passes so
that the work pieces 224 traverse the cure oven 215 multiple times,
despite the cure oven 215 as a whole constituting one workstation
WS9. The passes of the conveyor 207 can be parallel, back-and-forth
passes. In some constructions, the conveyor 207 makes at least
three such passes through the cure oven 215. Each pass can be a
full-length pass as shown. In addition, the cure oven 215 extends
completely or in large part over top of the workstations WS1-WS8
(e.g., arranged directly above rather than offset in plan view).
The disclosed configuration increases the residence time of the
work pieces 224 within the cure oven 215 without expanding the
length of the cure oven 215 so that the plan view footprint of the
coating system 200 is minimized and available floor space is
preserved. As shown in FIG. 10, the series of workstations WS1-WS8
define a length L.sub.WS. Measured parallel to the length L.sub.WS
of these workstations, the cure oven 215 extends the same length
L.sub.WS. More generally, the cure oven 215 has a length no more
than 1.1 times the length L.sub.WS of the series of workstations
WS1-WS8 by which the work pieces 224 come to have the pre-cured
applied coating. Moreover, to ensure compact plan view footprint,
the respective lengths of the workstations WS1-WS8 and the cure
oven 215 can be arranged with at least one completely overlapping
the other. In other constructions, at least 90 percent of the
length of each is overlapping with the other, referring again to
the lengths of the workstations WS1-WS8 and the cure oven 215. For
any given conveyor speed, a residence time of any work piece 224 in
the cure oven 215 is more than double a total residence time within
the series of workstations WS1-WS8. It is also noted that a
majority of a plan view width of each of the series of workstations
WS1-WS8 and the cure oven 215 are overlapping (FIG. 9), and in some
constructions define at least a mutual 90 percent overlap, similar
to the description directly above. This results from the conveyor
207 not deviating from a linear path when viewed in plan view
(despite the numerous vertical level changes shown in FIG. 10).
[0035] The sequential runs of the conveyor 207 through the cure
oven 215 can define ascending sub-levels within the second level
LV2. As illustrated, the odd number (e.g., three) of serpentine
runs through the cure oven 215 result in the work pieces 224 being
conveyed out of an outlet of the cure oven 215 at the first end,
adjacent the loading station 203 or first end. From the cure oven
outlet, the conveyor 207 carries the work pieces 224 back toward
the second end and the unloading station 205. This run of the
conveyor, which defines a cooling zone or cooling path, is located
at a third level LV3 that is above the second level LV2 defined by
the cure oven 215 (and may be in fact directly above the cure oven
215). Upon reaching the second end, the conveyor 207 returns the
work pieces 224 to the unloading station 205 at the first level
LV1. The now empty conveyor 207 returns to the loading station 203
by a conveyor run extending through a fourth level LV4 above all
the preceding levels. Along this final return path toward the
loading station 203, the carriers 220 can be cleaned at one or more
cleaning workstations WS10, WS11 (e.g., paint strip and RO
rinse).
[0036] Turning now to the cross-section of FIG. 11, it is shown
that each carrier 220 can be configured to carry a plurality of
like or dissimilar work pieces 224 (e.g., work pieces of the same
type but different sizes). The conveyor track on the left supports
a first carrier 220 having seven work pieces 224 mounted thereon,
and a second carrier 220 on the right conveyor track is similarly
loaded. As shown, each carrier 220 forms a laterally extending load
bar between the two flanks of its associated conveyor track, e.g.,
the two chains 209A or the two chains 209B. The carriers 220 can be
integrated with the chains 209 or removably attachable. The
configuration of the system is configured for very high throughput
by combining the advantages of a continuous flow-through monorail
system with the concept of two parallel chains and load bars
oriented across the transverse axis of the machine. As shown in
FIGS. 11 and 12, each carrier 220 includes a plurality of laterally
spaced hooks 227, the hooks 227 having barbed ends 229 (FIG. 12).
The hollow work pieces 224 are loaded by sliding them over the
barbed ends 229 onto the hooks 227. The work pieces 224 are either
positively snapped onto the barbed ends 229 or merely passively
retained from sliding back off. The barbed hooks 227 allow the work
pieces 224 to be retained despite the hooks 227 (or the carriers
220 as a whole) being pivotally supported by the conveyor at
respective points P, e.g., by journal bearings. As shown in FIG.
12, the conveyor travels either right or left and the carriers 220
with the hooks 227 are configured to rotate about an axis into the
page, perpendicular to the conveyance direction. While this may
induce some swinging during operation as shown by the double arrow
in FIG. 12, this movement helps assist in liquid drainage and thus
the prevention of pooling of the process fluids on the work pieces
224. In some constructions, the hooks 227 may assume a canted
attitude when loaded with the work pieces 224 due to the resulting
center of gravity. For example, FIG. 12 illustrates the vertical
leg of each hook 227 being tilted clockwise several degrees from a
straight upright attitude.
[0037] The system 200 as shown in FIGS. 9-12 can be used with other
types of work pieces and other types of carriers, including but not
limited to those of other embodiments contained herein. The system
200 can be operated with one or multiple types of work pieces at a
given time, or may be reconfigurable (e.g. by swapping carriers) to
accommodate a change in the work pieces.
* * * * *